On May 25, 2012, at 12:16 PM, Don Green wrote:
> Given the output of Racket's read-words/line function, which produces a list > of lists. Each word is in a list, each group of words on a line is in a list, > all within a list. > > Any ideas on how to sort on the car (first element) of each list that > corresponds to a line? > > In other words, I want to sort lines based on the first word on a line. I > want to keep the lines intact. > Thanks. > ____________________ > Racket Users list: > http://lists.racket-lang.org/users #lang racket (require 2htdp/batch-io rackunit) ;; --- answer to your question: (define (answer file) (sort (read-words/line file) string<=? #:key first)) ;; --- test set up (define content #<< eos This is a silly sample file. Do you think it is long enough? Or should I add a line? eos ) (define expected #<< eos Do you think it is long enough? Or should I add a line? This is a silly sample file. eos ) (define file (path->string (make-temporary-file "tst~a"))) (with-output-to-file file #:exists 'replace (lambda () (for ((ch content)) (display ch)))) ;; --- test (check-equal? (with-output-to-string (lambda () (for ((ln (answer file))) (displayln (string-join ln))))) expected) ____________________ Racket Users list: http://lists.racket-lang.org/users
